Email messages are transmitted from senders to recipients through networks such as local area networks or wide area networks such as the Internet. In many cases, a message is composed by a sender and sent via a mail server associated with the sender to a mail server associated with one or more recipient of the message. The mail server associated with the recipient can deposit the message into a mail folder or electronic mailbox that corresponds to the recipient. Additionally, depending on network conditions, routing conditions or other variables, a message may also be relayed via a relay mail server that is in communication with the mail server associated with the sender and the mail server associated with a recipient.